1. Field of the Invention
The present invention regards the subject of remote assistance and preventive servicing of electric appliances, particularly household electric appliances.
2. Prior Art
This subject was faced by the same Applicant in WO 99/43068. Such document describes a system for monitoring household appliances installed in the same household environment, whose control systems are prearranged for generating information of functional, diagnostic and statistical type, useful for technical servicing. The information generated by the household appliances is entered into a local area network, connected to which is a monitoring device, configured to gather the abovementioned information. The local network is represented by the same household is electric system, the communication system being of the power line communication type: for such purpose, the monitoring device and the household appliances of the system are provided with respective power line modems which allow connection to said local network. The monitoring device is prearranged for storing information gathered from the household network and subsequently showing them inside the household environment, for example by means of a display thereof. In a possible implementation, the monitoring device may be provided with a telephonic modem, such as a wireless telephonic modem according to the GSM European standard, to transmit information outside the household environment, towards a remote centre for technical assistance.
In this known embodiment, the abovementioned monitoring device meets the gateway functions, i.e. the functions of a device that allows interconnecting networks that use different architectures to each other, in particular with the aim of transferring the information gathered on the local electric mains network towards the outside of the household environment.
The solution described in this document has the drawback of exclusively taking into account electric appliances having inside a suitable communication device, being distinct from the digital control system of said appliances and communicating therewith by means of a suitable direct wired connection, incorporating the hardware and software means required for connecting to a local network based on PLC (Power Line Communication). This implies constraining the electric appliance to a determined communication technology that could make it obsolete shortly thereafter and, at the same time, it necessarily implies significant increase of costs for the appliance itself, hence seriously jeopardising its competitiveness in the market.
From WO 02/21664, of the same Applicant, methods, systems and apparatus are known, designed to allow an electric appliance to transmit a sequence of K bits (or a sequence of K digital or binary information), associated to an analogous sequence of consecutive K mains periods, through the variation of a quantity is representative of the electric energy consumed by the same appliance during each mains period of the abovementioned sequence of consecutive K mains periods. The term “mains periods” is used herein to indicate the time interval elapsed between two zero-crossings of the electric mains alternating voltage. The general teachings mentioned of the cited prior document, regarding the techniques employed to attain the abovementioned transmission, are deemed to be incorporated in the present description.
The variation of the value of a quantity representative of the electric energy consumed during the generic network period is performed, according to WO 02/21664, by the control system of the electric appliance through the variation of the value of the voltage applied to an electric load of the appliance itself and, consequently, of the current or power absorbed by the load at issue. The abovementioned variation is attained by means of a triac, which drives the load at issue of the electric appliance.
The information sent to the electric appliance in the described manner may be received by interposing a monitoring device between the power supply cable of the appliance and the related power socket. This monitoring device is capable of measuring, within each network period, the value of the abovementioned quantity that is representative of the electric energy consumed within the mains period, comparing such values with a suitable reference value and generating binary information depending on the result of such comparison.
A block diagram of the monitoring device according to WO 02/21664 is represented in FIG. 1, indicated with SA as a whole. As mentioned, the device SA essentially serves as a device for receiving digital information sent by the electric appliance associated thereto, indicated in the figure with HA, and is made up of the following three main functional blocks: a so-called power meter PM, a microcontroller M1 and a communication node N which controls the bidirectional communication with a local area network HN (Home Network). The information, sent according to WO 02/21664 by the electric appliance HA through the power supply cable thereof connected to the electric system Vac, are captured by the device PM, decoded by the microcontroller M1 and transmitted to the network HN through the communication node N.
The power meter PM is represented by a commercial measuring device, and specifically the CS5460 device of the US company Cirrus Logic, such device allowing to perform accurate measurements of electrical quantities that are representative of the energy consumed by the appliance HA within each period of the mains voltage.
The microcontroller M1 constantly dialogues with the power meter PM through a special fast communication line SL1 (for example a synchronous serial line such as a SPI, in the mentioned case of Cirrus Logic CS5460 device), with the aim of obtaining the abovementioned value of the quantity representative of the electric energy consumed during a generic mains period by the appliance HA. Subsequently, the same microcontroller M1 compares, with a determined reference value, the value previously obtained through the PM and, according to the result of the comparison, it generates a high or low logic value according to determined decoding criteria. In such manner, the microcontroller M1 performs, through the execution of suitable software routines, the decoding of the information sent by the electric appliance HA through the variation of the value of the quantity representative of the electric energy consumed by the appliance during each mains period and, after having suitably processed the information, it sends the latter, through a suitable communication line SL2, to the communication node N, which is connected to the local network HN.
Lastly, the communication node N is formed by two parts: a further microcontroller NC, which implements the communication protocol, and a transceiver PLM, which is the device that exchanges information with the local area network HN. Also in the case described by WO 02/21664 the local area network HN is represented by the same electric system of the household environment, given that the communication system is of the power line communication type.
The device SA of WO 02/21664 has the apparent advantage of performing two complementary functions at the same time: precise measurement (due to the high accuracy which is typical of the commercial “power meter” devices of the aforementioned type) of the electric energy consumptions associated to the appliance HA and the decoding of the digital information sent by the same appliance HA through the variation of the value of the quantity representative of the electric energy consumed during a generic mains period by the appliance. The device SA also has the advantage of performing the function of proxy with respect to the electric appliance HA, i.e. allowing the latter to dialogue, through the communication node N, with the local area network HN, without requiring the appliance HA be directly interfaced with said local network HN and control the related communication protocol: in such a manner, the cost associated to the connection of the appliance HA with the local network HN is totally charged on the device SA and thus no economical detriment is provided for such appliance HA.